The dominant copper-containing minerals in most copper sulfide deposits are chalcopyrite, cubanite and bornite. Chalcocite, covelite and in some cases enargite or tennantite are also present. The gangue mineral sulfides sometimes have pyrite and pyrrhotite present, many of these along with lesser quantities of host or gangue minerals report to the final flotation concentrate.
High-grade, copper sulfide concentrates, (typically greater than about 25% Cu weight/weight), are commonly treated by pyrometallurgical routes, whereas hydrometallurgical routes are generally favoured for the lower-grade, or impurity bearing copper concentrates. The economically and technically most favourable processing route can also be influenced by the concentration of minor amounts of valuable metals such as cobalt and nickel, or payable precious metals such as silver, gold, palladium and platinum, as well as contamination by radioactive elements such as uranium, thorium, radium, lead, bismuth or polonium and deleterious metals such as arsenic, present in the feed material. Hydrometallurgical processing routes are generally more energy consuming than smelting, because the heat of combustion of the concentrates is not efficiently utilized.
The three dominant pyrometallurgical routes for high-grade, copper sulfide concentrates are;                a) smelting to a matte followed by converting to blister copper,        b) direct to blister smelting and        c) oxidative roasting.        
The efficiency of the smelting technology is determined by, amongst other things, the Cu/S ratio and the concentration of slag forming components, especially iron, magnesium and silica. Conventional smelting processes are generally not applicable to lower grade copper concentrates. Not all of the copper content of the original feed is recovered as blister copper, with the remaining copper reporting to the slag and to the smelter dusts or fumes recovered from the smelter off-gases.
Roasting of copper concentrates requires the conversion of the copper content to a water-soluble or sulfate form, which is recovered from the roaster calcine by leaching, followed by solvent extraction and electrowinning. Roasting is often inefficient because copper-containing insoluble ferrite phases can form during the roasting stage and lock some copper and valuable by-products such as cobalt.
Many hydrometallurgical processes have been described for treating copper-containing concentrates, for example;    Burkin A. R, Chemical Hydrometallurgy, 1952-1994, Trans. Inst Min. Metall., 103, 1994, C169-C176.    Dreisinger, D, Copper leaching from primary sulfides: Options for biological and chemical extraction of copper, HYDROMETALLURGY, 2006, 83, 10-20.
Few of the proposed processes have attained full-scale commercial development, and most give little or no attention to removal of impurity or penalty elements, including radionuclides, or disposal of these elements by environmentally benign methods. Hydrometallurgical processes for copper concentrates struggle to compete economically against pyrometallurgical steps such as smelting, for reasons including:                a) effective removal of impurity or penalty elements,        b) cost of power,        c) environmentally acceptable disposal of residues, and        d) difficulty in precious metal recovery.        
Economic performance of the smelting routes in particular is improved if copper concentrates can be upgraded in their copper content or deleterious impurities can be removed before being fed to the smelting furnaces. But the source or production of copper sulfate solution for ‘metathesis’ reactions, and deportment of the impurity, radioactive or value elements, is not considered in most treatment routes, and nor is the disposal of residues and effluents.
Various means of hydrometallurgical upgrading of the copper content of a copper concentrate have been proposed, including ‘metathesis’ leaching which displaces the iron content of the concentrate with an equivalent stoichiometric amount of copper. The so-called ‘metathesis’ process, in which the chalcopyrite component of the concentrate is reacted with a copper sulfate solution to produce low-iron copper sulfide (e.g. digenite) and an acidic, ferrous sulfate solution, can be represented.3CuFeS2+6CuSO4+4H2O→5Cu1.8S+3FeSO4+4H2SO4  (1)
A similar reaction also occurs for any bornite present in the copper concentrate.3Cu5FeS4+6CuSO4+4H2O→5Cu1.8S+6Cu2S+3FeSO4+4H2SO4  (2)
Similar reactions occur when cobalt is recovered from a blend of cobaltite and chalcopyrite minerals or carrollte.
The descriptions of processes which involve metathesis reactions do not generally include the source of copper sulfate, the deportment of impurity, valuable and radioactive elements, or the treatment and disposal of residues and effluents.
One or both of these above reactions (1) and (2) are referred to directly or indirectly in U.S. Pat. Nos. 2,568,963, 2,662,009, 2,744,172 and 4,024,218, Canadian Patent No. 1 258 181, South African Patent No. 2007/01337, and WIPO Patent Publication No. WO 2004/106561. All of these patents propose to forward the upgraded copper sulfide concentrate, which typically contains above 50% Cu, to either a smelter or treatment by other means.
The flowsheets in these patent specifications contain several deficiencies, such as identifying an economic source of copper sulfate solution, incomplete separation of iron and copper in solution, the requirement of additional flotation steps, economic recovery of precious metals from the residues, or have difficulty removing other impurities such as radionuclides, including uranium and its decay elements, and the final destination or treatment route of residues and effluents which can be problematic.
The present invention aims to at least partially overcome some of these deficiencies, and also addresses more importantly the removal of uranium, along with the other radionuclides which are its decay elements, that would otherwise limit or penalise the processing of the concentrate in an off-shore or remote smelter, or prohibit or restrict the international trade of copper concentrate across international borders. Thus the present invention aims to reduce the level of uranium and other radionuclides in a radioactive or ‘dirty’ copper concentrate to allow the concentrate to be smelted within the limits of national or international regulations.
Furthermore, the present invention attempts to assist in minimising the overall capital and operating cost components of the total processing of concentrates, as well as allowing disposal of treatment residues by means acceptable to regulatory authorities.
References to prior art in this specification are provided for illustrative purposes only and are not to be taken as an admission that such prior art is part of the common general knowledge in Australia or elsewhere.